package org.apache.lucene.store;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.util.ArrayList;
import java.io.Serializable;

class RAMFile implements Serializable {

	private static final long serialVersionUID = 1l;

	private ArrayList buffers = new ArrayList();
	long length;
	RAMDirectory directory;
	long sizeInBytes; // Only maintained if in a directory; updates
						// synchronized on directory

	// This is publicly modifiable via Directory.touchFile(), so direct access
	// not supported
	private long lastModified = System.currentTimeMillis();

	// File used as buffer, in no RAMDirectory
	RAMFile() {
	}

	RAMFile(RAMDirectory directory) {
		this.directory = directory;
	}

	// For non-stream access from thread that might be concurrent with writing
	synchronized long getLength() {
		return length;
	}

	synchronized void setLength(long length) {
		this.length = length;
	}

	// For non-stream access from thread that might be concurrent with writing
	synchronized long getLastModified() {
		return lastModified;
	}

	synchronized void setLastModified(long lastModified) {
		this.lastModified = lastModified;
	}

	final synchronized byte[] addBuffer(int size) {
		byte[] buffer = newBuffer(size);
		if (directory != null)
			synchronized (directory) { // Ensure addition of buffer and
										// adjustment to directory size are
										// atomic wrt directory
				buffers.add(buffer);
				directory.sizeInBytes += size;
				sizeInBytes += size;
			}
		else
			buffers.add(buffer);
		return buffer;
	}

	final synchronized byte[] getBuffer(int index) {
		return (byte[]) buffers.get(index);
	}

	final synchronized int numBuffers() {
		return buffers.size();
	}

	/**
	 * Expert: allocate a new buffer. Subclasses can allocate differently.
	 * 
	 * @param size
	 *            size of allocated buffer.
	 * @return allocated buffer.
	 */
	byte[] newBuffer(int size) {
		return new byte[size];
	}

	// Only valid if in a directory
	long getSizeInBytes() {
		synchronized (directory) {
			return sizeInBytes;
		}
	}

}
